This invention relates generally to the field of telephone protector modules of a type adapted to protect the tip and ring circuits of an individual subscriber pair. Modules of this general type are known in the art, and are normally engaged upon a telephone protector block mounted upon a main frame in a telephone office. The invention lies in specific constructional details permitting economies of manufacture, and improved reliability in operation.
Devices of this type when installed are usually in juxtaposed relation on all sides relative to similar devices which serve to protect other subscriber pairs. Under such conditions, only an outer wall of the module housing is visible to service personnel, which wall usually mounts a small T-shaped handle which enables the module to be manually disengaged from the block.
In the De Luca et al. U.S. Pat. No. 3,947,730 granted Mar. 30, 1976 and assigned to the same assignee as the instant application, there is disclosed a gas tube type protector module which includes a single wad, and outer end of which projects through a bore in the handle to expose an outermost tip thereof when a single heat sensitive means is actuated. In the disclosed device, a single gaseous discharge tube protects both the tip and ring circuits, and heat developed in either part of the tube will actuate the single heat sensitive means to ground the tip and ring circuits.
However, the bulk of protector modules of this type are of the carbon arc variety with a separate heat sensitive means for each of the tip and ring circuits. In such construction, either heat sensitive means may become operative without affecting the condition of the other. U.S. Pat. No. 4,091,435 granted Apr. 23, 1978 to Om P. Ahuja, and assigned to the same assignee as the instant application, provides separate individual means for each circuit in the module, but has a disadvantage in that the end of the indicator projects through an opening in a housing wall rather than a bore in the handle supported by that wall, for the reason that the indicators are positioned such that they cannot extend through the handle. Since the indicators do not project past the outer surface of the handle, they are not readily visible to service personnel, and are correspondingly difficult to locate.